The antonyms for the phrase "put lock on" include "remove lock," "unlock," "open," and "release." When you remove a lock from something that was previously locked, you are effectively taking away the barrier that once prohibited access. Unlocking a lock also allows for entry without any prior preparation or tools. If something is open, it is accessible without any restrictions or barriers. Release implies that something was previously captured or detained, and is now set free or allowed to move freely. These antonyms can be useful when trying to express ideas of accessibility, freedom, or a lack of restriction.